CTA Images Research Articles

Clinical and prognostic correlates of pulmonary congestion in coronary computed tomography angiography data sets

BackgroundSigns of pulmonary congestion obtained from cardiac computed tomography angiographic (coronary CTA) images have not previously been related to clinical congestion or outcome and the clinical value is, therefore, unknown. Our objective was to test the hypothesis that signs of pulmonary congestion predict clinical heart failure and adverse outcome in patients with myocardial infarction. MethodsCoronary CTA was performed before invasive treatment in 400 prospectively included patients with non ST segment elevation myocardial infarction in an observational study. Using a previously described chest computed tomography evaluation algorithm, patients were classified as having “no congestion”, “mild to moderate congestion” or “severe congestion”. ResultsUsing multivariate analyses, presence of pulmonary congestion on coronary CTA images was associated with age, female gender, left ventricular ejection fraction (LVEF) and left atrial size. The diagnostic accuracy for predicting clinical heart failure, defined as Killip class >1, was: sensitivity: 83%, specificity: 69%, positive predictive value: 25%, and negative predictive value: 97%. The median follow-up time was 50 months and the study end-point of death or hospitalization due to heart failure was reached in 68 (16%) patients. In a Cox proportional hazards model with adjustments for known risk factors and Killip class, the presence of “mild to moderate congestion” and “severe congestion” was independently associated with adverse outcome (Hazard ratio: 2.6 (95% CI:1.3–5.0) and 3.2 (1.3–7.5)). ConclusionSigns of pulmonary congestion on coronary CTA images are closely correlated to cardiac dysfunction, predict clinical heart failure, and provide prognostic value independent of LVEF and Killip class.

Comparison of CTA- and DSA-Based Collateral Flow Assessment in Patients with Anterior Circulation Stroke.

Collateral flow is associated with clinical outcome after acute ischemic stroke and may serve as a parameter for patient selection for intra-arterial therapy. In clinical trials, DSA and CTA are 2 imaging modalities commonly used to assess collateral flow. We aimed to determine the agreement between collateral flow assessment on CTA and DSA and their respective associations with clinical outcome. Patients randomized in MR CLEAN with middle cerebral artery occlusion and both baseline CTA images and complete DSA runs were included. Collateral flow on CTA and DSA was graded 0 (absent) to 3 (good). Quadratic weighted κ statistics determined agreement between both methods. The association of both modalities with mRS at 90 days was assessed. Also, association between the dichotomized collateral score and mRS 0-2 (functional independence) was ascertained. Of 45 patients with evaluable imaging data, collateral flow was graded on CTA as 0, 1, 2, 3 for 3, 10, 20, and 12 patients, respectively, and on DSA for 12, 17, 10, and 6 patients, respectively. The κ-value was 0.24 (95% CI, 0.16-0.32). The overall proportion of agreement was 24% (95% CI, 0.12-0.38). The adjusted odds ratio for favorable outcome on mRS was 2.27 and 1.29 for CTA and DSA, respectively. The relationship between the dichotomized collateral score and mRS 0-2 was significant for CTA (P = .01), but not for DSA (P = .77). Commonly applied collateral flow assessment on CTA and DSA showed large differences, indicating that these techniques are not interchangeable. CTA was significantly associated with mRS at 90 days, whereas DSA was not.

Reduction of misregistration on cerebral four-dimensional computed tomography angiography images using advanced patient motion correction reconstruction.

The aim of this study was to evaluate whether advanced patient motion correction (APMC) can reduce the misregistration of pixels between the different X-ray tube positions in four-dimensional CT angiography (4D-CTA). Eight patients with intracranial aneurysms were included in this retrospective study. We compared the CTA images with APMC reconstruction and half-scan reconstruction with regard to the following 3 items: (1) bone misalignment area; (2) image noise; and (3) aneurysm volume change. The bone misalignment area and image noise were significantly reduced in the APMC images, as compared to that in the half-scan reconstruction images (bone misalignment area: 33.0±18.1cm(3) vs 152.0±72.2cm(3), respectively; p<0.001) (image noise at pons: 9.70±2.58 vs 15.16±5.02, respectively, p<0.001). The aneurysm volume and volume variance were significantly smaller in the APMC reconstruction than those in the half-scan reconstruction (volume: 1107.2±1813.8mm(3) vs 1135.1±1853.8mm(3); p<0.05; coefficient of variation: 0.0291±0.014 vs 0.0463±0.026, p<0.05, respectively). Our results show that APMC reduces the reconstruction related misregistration between the cardiac phases compared to half-scan reconstruction.

VS09. Fenestrated EVAR With 3D CTA Image Fusion

VS09. Fenestrated EVAR With 3D CTA Image Fusion

CT Angiography 영상에서 대동맥 추출을 위한 혈관 분할 알고리즘 성 평가

세계보건기구협회에의 통계에 따르면 심장 혈관 질환의 발병률이 가장 높은 것으로 알려져 있다. CTA영상을 사용하여 관상동맥 및 대동맥 질환을 치료 및 검사할 수 있다. 혈관을 3차원으로 복원하는 과정이 의사의 숙련도에 따라 결과가 상이하며 복원 시간이 길다는 단점이 있으며 이를 극복하고자 자동으로 정확한 혈관을 추출하는 연구들이 진행되어 왔다. 본 논문에서는 자동 및 반자동 분할 기법인 Region Competition, Geodesic Active Contour(GAC), Multi-atlas based segmentation, Active Shape Model(ASM) 알고리즘을 CTA영상에 적용하여 대동맥 기부를 추출하였으며 하우스도르프 거리, 볼륨, 영상처리속도, 사용자 관여 여부, 그리고 관상동맥 심문 검출률을 비교 및 분석하였다. 추출된 3차원 대동맥 모델 중 가장 높은 정확도를 나타낸 알고리즘은 GAC인 반면 사용자 관여가 가장 높았기 때문에 실제 시술에 적용하기 위해서는 자동 분할 알고리즘 개선이 필요하다 World Health Organization reported that heart-related diseases such as coronary artery stenoses show the highest occurrence rate which may cause heart attack. Using Computed Tomography angiography images will allow radiologists to detect and have intervention by creating 3D roadmapping of the vessels. However, it is often complex and difficult do reconstruct 3D vessel which causes very large amount of time and previous researches were studied to segment vessels more accurate automatically. Therefore, in this paper, Region Competition, Geodesic Active Contour (GAC), Multi-atlas based segmentation and Active Shape Model algorithms were applied to segment aortic root from CTA images and the results were analyzed by using mean Hausdorff distance, volume to volume measure, computational time, user-interaction and coronary ostium detection rate. As a result, Extracted 3D aortic model using GAC showed the highest accuracy but also showed highest user-interaction results. Therefore, it is important to improve automatic segmentation algorithm in future

Prevalence of Intracranial Aneurysms in Patients with Connective Tissue Diseases: A Retrospective Study.

Few studies have examined the prevalence of intracranial aneurysms in connective tissue diseases such as Marfan syndrome, Ehlers-Danlos syndrome, neurofibromatosis type 1, and Loeys-Dietz syndrome. We studied the prevalence of intracranial aneurysms and other intracranial neurovascular pathologies such as arteriovenous malformations and intracranial dissections, in these 4 patient populations. We retrospectively reviewed all patients who had a clinical diagnosis of Marfan syndrome, Ehlers-Danlos syndrome, neurofibromatosis type 1, or Loeys-Dietz syndrome who underwent MRA, CTA, and/or DSA imaging of the intracranial circulation between January 1, 2005, and January 31, 2015. The presence, location, and maximum dimensions of intracranial aneurysms were catalogued. Other neurovascular findings studied included intracranial dissections and arteriovenous fistulas and shunts. Baseline data collected included demographic characteristics (sex, age, smoking history), imaging modality, and cardiovascular comorbidities. The prevalence of intracranial saccular and fusiform aneurysms was as follows: 14% (8/59) among patients with Marfan syndrome, 12% (12/99) among patients with Ehlers-Danlos syndrome, 11% (5/47) among patients with neurofibromatosis type 1, and 28% (7/25) among patients with Loeys-Dietz syndrome. Intracranial dissections were found in 2 patients (3%) with Marfan syndrome and 1 patient (1%) with Ehlers-Danlos syndrome. No intracranial dissections were found in patients with neurofibromatosis type 1 or Loeys-Dietz syndrome. Patients with connective tissue disorders, including Marfan syndrome, Ehlers-Danlos syndrome, neurofibromatosis type 1, and Loeys-Dietz syndrome, have a high prevalence of intracranial aneurysms.

Comparison of image quality of atrial fibrillation and normal sinus rhythm ratients on single beat volumetric CT scanner, initial experience with a new CT scanner

Background: Images of patients with arrhythmias, particularly atrial fibrillation (AF), are often difficult to acquire with coronary CTA due to challenges in image acquisition and temporal resolution. We propose to evaluate image quality (IQ) expressed as Likert scale, signal to noise ratio (SNR), and contrast to noise ratio (CNR) from coronary CTA images acquired with a volumetric single beat CT scanner. Our hypothesis was that there is no significant difference in IQ between patients with and without AF.

Hemodynamics of left internal mammary artery bypass graft: Effect of anastomotic geometry, coronary artery stenosis, and postoperative time

Although the left internal mammary artery (LIMA) bypass graft is the best choice for surgical revascularization, its hemodynamics are still complex and can result in long-term graft failure. Here, we performed a hemodynamic analysis of the LIMA-coronary artery with end-to-side/side-to-side anastomoses based on 15 patient-specific CTA images at various postoperative periods. We hypothesize that hemodynamic patterns are determined by the interplay of LIMA geometry, anastomotic configuration, and severity of native coronary artery stenosis, which are strongly affected by the postoperative time. A 3D finite volume method with the inlet pressure wave and outlet resistance boundary conditions was used to compute the distribution of pressure and flow, from which the time-averaged wall shear stress (TAWSS), oscillation shear index (OSI), time-averaged WSS gradient (TAWSSG), and transverse WSS (transWSS) were determined. To characterize the hemodynamic environment, we defined surface area ratios of low TAWSS (≤4dynes/cm2), high OSI (≥0.15), TAWSSG (≥500dynes/cm3), and transWSS (≥6dynes/cm2) in the LIMA graft and at the anastomosis between LIMA graft and coronary artery. These ratios were determined by the interplay of multiple morphometric parameters in the LIMA-coronary artery, but increased with postoperative time. These findings have significant implications for understanding LIMA graft patency.

Abstract 13: Wall Shear Stress Associated to Intracranial Aneurysm Wall Inflammation

Introduction: Inflammation has been proposed as a possible mechanism involved in the degradation and weakening of the walls of intracranial aneurysms. Hypothesis: Abnormal wall shear stress (WSS) levels induce wall inflammation which then affects the wall structure and mechanics Methods: A total of 20 aneurysms which underwent surgical clipping were studied. Patient-specific computational fluid dynamics models were constructed from pre-surgical CTA images. Numerical simulations were carried out using pulsatile flows. After clipping the aneurysm, a tissue sample was resected from the dome and analyzed histologically with CD45 to search for evidence of wall inflammation. For analysis, the aneurysm series was divided in two different manners. First, aneurysms were classified into an “inflammation” group if the number of CD45+ cells was larger than the median of CD45+ cells in the entire sample of 20 aneurysms; otherwise they were classified as “no-inflammation”. Hemodynamic variables were then statistically compared between these two groups. Secondly, aneurysms were subdivided into three groups according to their mean WSS: 1) “low WSS” if WSS&lt;0.5*median(WSS), 2) “high WSS” if WSS&gt;2*median(WSS), and 3) “mid WSS” otherwise. The numbers of CD45+ cells in each group were then statistically compared. Results: Aneurysms in the “inflammation” group had significantly larger mean WSS (p=0.018), shear rate (p=0.015), vorticity (p=0.018), and viscous dissipation (p=0.015) than aneurysms in the “no-inflammation” group. Conversely, aneurysms in the “high WSS” group had significantly larger numbers of CD45+ cells (p=0.0046) than the “mid WSS” and “low WSS” groups. Interestingly, aneurysms with stable flow patterns also tended to have larger numbers of inflammatory cells (p=0.040) than aneurysms with unstable flows. Conclusion: These preliminary results suggest that there is a connection between intra-aneurysmal flow characteristics and wall inflammation in cerebral aneurysms. In particular, inflamed walls seem to be associated with higher levels of wall shear stress.

Abstract WP121: An Evaluation of Hemodynamics Across Intracranial Steno-occlusive Lesions by Computational Fluid Dynamics

Introduction: Intracranial atherosclerotic steno-occlusive disease (ICAS) is a major cause of stroke worldwide and portends a high risk of recurrence. Computational fluid dynamics (CFD) is a novel technique developed to solve and analyze the dynamic effects of fluid flow. We aimed to analyse hemodynamics across ICAS using CFD on processed CTA images and explore the correlation between the degree of arterial stenosis and hemodynamic flow status. Methods: We recruited patients with symptomatic ICAS from Acute Stroke Unit, Prince of Wales Hospital. All patients received CTA and DSA as vascular workup. Using CFD analysis of processed CTA images, we first defined the hemodynamic parameters, including pressure difference, pressure ratio, pressure gradient, shear strain rate ratio (SSR), wall shear stress (WSS) ratio and velocity ratio, across the stenosed vessels, and then we correlated the severity of stenosis as defined by DSA, with these parameters. Results: Among the 53 recruited patients (mean age 62.9 years, 69.8% males), 45 (85%) had lesions in the anterior circulation. The severity of stenosis showed a weak-to-moderate correlation with pressure difference (rs=0.392, p=0.004), pressure ratio (rs=-0.429, p=0.001) and pressure gradient (rs=0.419, p=0.002). There was no significant correlation between the severity of stenosis with SSR ratio, WSS ratio and velocity ratio. Among patients with anterior circulation stroke or TIA, the severity of stenosis showed a weak to moderate correlation with pressure difference (rs=0.381, p=0.01), pressure ratio (rs=-0.426, p=0.004) and pressure gradient (rs=0.407, p=0.005). For patients with posterior circulation stroke or TIA, the severity of stenosis was strongly correlated with pressure difference (rs=0.714, p=0.047) and pressure ratio (rs=-0.714, p=0.047); and very strongly correlated with velocity ratio (rs=0.833, p=0.01). Conclusions: The severity of ICAS showed only weak-to-moderate correlation with hemodynamic parameters across the culprit lesion. Thus, risk stratification and treatment based solely on stenotic severity may be inadequate. Our findings may guide further research in estimating stroke risks and selection of high-risk patients who may benefit from adjunctive treatments.

Enlarged and Colored Enhanced 3D Printing of Renal Artery Aneurysms for Improved Imaging and Treatment Planning

Three dimensional printing (3D printing) technology is increasingly used to improve results in many areas of medicine. Physical models produced by this technology allow better appreciation of complex anatomical and pathologic conditions. In cardiovascular medicine and surgery, 3D modeling has been reported to be of help in treatment planning of abdominal aortic aneurysm, especially in cases of complex angulations and branching at the aneurysm neck. Here we report the use of 3D printing in cases of renal aneurysms. Enhanced 3D models of CTA images of renal aneurysms were prepared in house using common and freely available software programs, and an accurate desktop 3D printer. Eight reconstructed models were enlarged by a factor of 2 or more and then differentially painted to delineate normal arteries and aneurysmatic ones. These enhanced 3D solid models allowed visual and tactile inspection for a better appreciation of complex aneurysms. Color enhancement of these models added another dimension of comprehension, even for experienced surgeons and invasive radiologists, and allowed more accurate measurements of branch numbers, distances, and angles in space even with severe tortuosity. Endovascular use of covered stents and embolization techniques could be easily envisioned preoperatively. We conclude that enhanced, enlarged, and colored 3D printed models are a powerful tool for preoperative endovascular treatment planning of complex renal artery aneurysms.

Hemodynamics in stented vertebral artery ostial stenosis based on computational fluid dynamics simulations

Hemodynamic factors may affect the potential occurrence of in-stent restenosis (ISR) after intervention procedure of vertebral artery ostial stenosis (VAOS). The purpose of the present study is to investigate the influence of stent protrusion length in implantation strategy on the local hemodynamics of the VAOS. CTA images of a 58-year-old female patient with posterior circulation transient ischemic attack were used to perform a 3D reconstruction of the vertebral artery. Five models of the vertebral artery before and after the stent implantation were established. Model 1 was without stent implantation, Model 2–5 was with stent protruding into the subclavian artery for 0, 1, 2, 3 mm, respectively. Computational fluid dynamics simulations based on finite element analysis were employed to mimic the blood flow in arteries and to assess hemodynamic conditions, particularly the blood flow velocity and wall shear stress (WSS). The WSS and the blood flow velocity at the vertebral artery ostium were reduced by 85.33 and 35.36% respectively after stents implantation. The phenomenon of helical flow disappeared. Hemodynamics comparison showed that stent struts that protruded 1 mm into the subclavian artery induced the least decrease in blood speed and WSS. The results suggest that stent implantation can improve the hemodynamics of VAOS, while stent struts that had protruded 1 mm into the subclavian artery would result in less thrombogenesis and neointimal hyperplasia and most likely decrease the risk of ISR.

Multidetector CT angiography in the diagnosis and classification of carotid–cavernous fistula

To evaluate the performance of multidetector computed tomography angiography (MDCTA) in identifying and classifying carotid-cavernous fistulas (CCFs). The neuro-interventional database was searched for patients with CCFs at four different institutions and for normal controls at one of the four institutions. Thirty-four patients were divided into the case group (direct type, n=8; indirect type, n=8) and the control group (n=18). Two readers retrospectively evaluated thin-section CTA images for the presence and laterality of four findings: (1) engorged ophthalmic vein, (2) engorged cavernous sinus, (3) similar enhancement of the cavernous sinus (CS) and internal carotid artery (ICA), and (4) greater enhancement of the CS than the transverse sinus (TS). Dehiscent ICA for the direct type was assessed only in the case group. Sensitivity, specificity, and inter-reader agreement were determined. Attenuation differences between the ICA and CS and between the CS and TS were compared across groups. The sensitivity/specificity for two engorgement and two enhancement findings were 81%/100%, 88%/94%, 100%/100%, and 88%/100%, respectively, for Reader 1, and 75%/100%, 75%/100%, 88%/100%, and 88%/100%, respectively, for Reader 2. Agreement between readers was excellent for all findings (κ>0.80). Dehiscent ICA identified the direct type with a sensitivity/specificity of 100%/75% for Reader 1 and 100%/88% for Reader 2 (κ=0.871). In the case group, the difference between ICA and CS attenuation values was significantly lower (180.1±76.6 versus 7.5±23.7; ⤳<0.001) and that between CS and TS were higher (-31.2±69 versus 102.6±59.3; ⤳<0.001). The area under the curve for the latter values was 0.95. The engorgement and enhancement categories in MDCTA may perform comparably in identifying CCFs and measurements of vessel attenuation differences may be of high diagnostic value. Dehiscent ICA can greatly aid in identifying the direct type.

Abstract 19190: Effectiveness of Supervised Exercise Therapy for the Treatment of Intermittent Claudication in Real-world Clinical Practice

Introduction: Guidelines recommend supervised exercise therapy (SET) as a first-line treatment for patients with intermittent claudication. In trials, SET has indeed been shown to be equally effective as endovascular revascularization in improving walking performance and quality of life. However, SET is an underutilized treatment and the effectiveness of a SET-first approach outside a trial setting is unknown. Hypothesis: We assessed the hypothesis that SET is an effective treatment for intermittent claudication in real-world clinical practice. Methods: In a single-center prospective cohort study, 204 patients with newly diagnosed intermittent claudication were referred to a physiotherapist for SET between August 2009 and December 2013. All patients underwent lower extremity CTA or MRA imaging. Significant stenosis was defined as ≥50% reduction in luminal diameter. Community-based SET was provided according to national guidelines. Freedom from endovascular or open surgical intervention at the last outpatient visit was considered as the primary outcome. Kaplan Meier estimate was used to determine freedom from intervention at 1 year. Results: Mean age was 70±10 years with 59% men and the common risk factors (77% hypertension, 31% diabetes, 46% smoking, 10% obesity) and comorbidities (32% and 23% history of ischemic heart or cerebrovascular disease, resp.). Median maximum walking distance on treadmill testing at baseline visit was 320 m (IQR 150-510 m). The majority (88%) of patients had significant femoropopliteal and/or crural disease. Only 4% had isolated aortoiliac and/or common femoral artery stenoses. Of the 204 referred patients, 84% followed the SET program. After 1 year follow up, 88% of patients were still free from endovascular or surgical intervention. Conclusions: In a real-world clinical setting, a SET-first approach is an effective treatment for intermittent claudication, preventing invasive treatment in most patients.

Automatic aortic root landmark detection in CTA images for preprocedural planning of transcatheter aortic valve implantation.

Transcatheter aortic valve implantation is currently a well-established minimal invasive treatment option for patients with severe aortic valve stenosis. CT Angiography is used for the pre-operative planning and sizing of the prosthesis. To reduce the inconsistency in sizing due to interobserver variability, we introduce and evaluate an automatic aortic root landmarks detection method to determine the sizing parameters. The proposed algorithm detects the sinotubular junction, two coronary ostia, and three valvular hinge points on a segmented aortic root surface. Using these aortic root landmarks, the automated method determines annulus radius, annulus orientation, and distance from annulus plane to right and left coronary ostia. Validation is performed by the comparison with manual measurements of two observers for 40 CTA image datasets. Detection of landmarks showed high accuracy where the mean distance between the automatically detected and reference landmarks was 2.81 ± 2.08 mm, comparable to the interobserver variation of 2.67 ± 2.52 mm. The mean annulus to coronary ostium distance was 16.9 ± 3.3 and 17.1 ± 3.3 mm for the automated and the reference manual measurements, respectively, with a mean paired difference of 1.89 ± 1.71 mm and interobserver mean paired difference of 1.38 ± 1.52 mm. Automated detection of aortic root landmarks enables automated sizing with good agreement with manual measurements, which suggests applicability of the presented method in current clinical practice.

VALIDATION OF [18F]-SODIUM FLUORIDE AS A MARKER OF ACTIVE CALCIFICATION AND HIGH-RISK CAROTID PLAQUE: A SUB-STUDY OF THE CANADIAN ATHEROSCLEROSIS IMAGING NETWORK (CAIN-2)

[18F]-sodium fluoride (NaF) positron emission tomography (PET) uptake may serve as an imaging-derived biomarker of active calcification. It is postulated that NaF binds to hydroxyapatite molecules that are expressed in regions with active calcification. We aimed to: 1. Validate NaF uptake imaged with PET/CT, as a direct marker of active calcification within carotid plaque, as determined by its association with intraplaque expression of hydroxyapatite; and 2. Determine whether NaF uptake is related to cerebrovascular events. Eleven patients (69 ± 5 years, 3 females) scheduled for carotid endarterectomy were prospectively recruited. Patients underwent NaF PET and contrast-enhanced CTA imaging of carotid vasculature. The bifurcation of the common carotid was used as a reference point; maximum NaF uptake normalized to blood (tissue to blood ratio - TBR) was measured at every PET slice extending 2 cm above and below the bifurcation. Following endarterectomy, excised carotid plaque was fixed, sectioned and stained with Goldner’s Trichrome (marker of hydroxyapatite expression). An electronic algorithm was applied to quantify hydroxyapatite expression on whole-slide digitized images. Using the distance from the bifurcation, pathology was aligned with CTA and co-registered with PET. To determine the relationship between NaF uptake and cerebrovascular events, bilateral carotid plaque was classified as either symptomatic (associated with cerebrovascular events) or clinically silent, asymptomatic plaque. Carotid endarterectomy was performed in 11 patients; one patient received a 2nd carotid endarterectomy due to bilateral disease. Two patients were excluded (intolerance to CT contrast agent and PET/CT misalignment). Staining was available for 8 excised plaques. NaF uptake was related to intraplaque hydroxyapatite expression (r=0.45, p<0.001) (Figure 1). NaF uptake was greater at the side of carotid endarterectomy (endarterectomy: 3.73±1.1 TBR vs. contralateral: 2.82±0.6 TBR, p=0.030). Symptomatic carotid plaque had evidence for greater NaF uptake (symptomatic plaque: 3.75±1.1 TBR vs. asymptomatic plaque: 2.79±0.6 TBR p=0.04) NaF uptake imaged with PET/CT is related to intraplaque expression of hydroxyapatite, which is expressed in regions with active calcific activity. NaF uptake was greater in plaque that was scheduled for endarterectomy, as well as symptomatic plaque associated with cerebrovascular events. NaF PET/CT may serve as a novel biomarker of active calcification and enable identification of high-risk patients. Larger outcome based follow-up studies are underway.

Cerebral Angiography for Evaluation of Patients with CT Angiogram-Negative Subarachnoid Hemorrhage: An 11-Year Experience.

CT angiography is increasingly used to evaluate patients with nontraumatic subarachnoid hemorrhage given its high sensitivity for aneurysms. We investigated the yield of digital subtraction angiography among patients with SAH or intraventricular hemorrhage and a negative CTA. An 11-year, single-center retrospective review of all consecutive patients with CTA-negative SAH was performed. Noncontrast head CT, CTA, DSA, and MR imaging studies were reviewed by 2 experienced interventional neuroradiologists and 1 neuroradiologist. Two hundred thirty patients (mean age, 54 years; 51% male) with CTA-negative SAH were identified. The pattern of SAH was diffuse (40%), perimesencephalic (31%), sulcal (31%), isolated IVH (6%), or identified by xanthochromia (7%). Initial DSA yield was 13%, including vasculitis/vasculopathy (7%), aneurysm (5%), arteriovenous malformation (0.5%), and dural arteriovenous fistula (0.5%). An additional 6 aneurysms/pseudoaneurysms (4%) were identified by follow-up DSA, and a single cavernous malformation (0.4%) was identified by MRI. No cause of hemorrhage was identified in any patient presenting with isolated intraventricular hemorrhage or xanthochromia. Diffuse SAH was due to aneurysm rupture (17%); perimesencephalic SAH was due to aneurysm rupture (3%) or vasculitis/vasculopathy (1.5%); and sulcal SAH was due to vasculitis/vasculopathy (32%), arteriovenous malformation (3%), or dural arteriovenous fistula (3%). DSA identifies vascular pathology in 13% of patients with CTA-negative SAH. Aneurysms or pseudoaneurysms are identified in an additional 4% of patients by repeat DSA following an initially negative DSA. All patients with CT-negative SAH should be considered for DSA. The pattern of SAH may suggest the cause of hemorrhage, and aneurysms should specifically be sought with diffuse or perimesencephalic SAH.

Bone-Subtracted Spinal CT Angiography Using Nonrigid Registration for Better Visualization of Arterial Feeders in Spinal Arteriovenous Fistulas.

Pretreatment diagnosis for the location of shunts and arterial feeders of spinal arteriovenous fistulas is crucial. This study aimed to evaluate the utility of subtracted CT angiography imaging by using nonrigid registration (R-CTA) in patients with spinal arteriovenous fistulas compared with conventional CTA imaging. The records of 15 consecutive subjects (mean age, 65 years; 2 women) who had undergone CTA and digital subtraction angiography for clinically suspected spinal arteriovenous fistula were reviewed. From CTA images obtained at the arterial and late arterial phases, warped images of the late arterial phase were obtained by using nonrigid registration that was adjusted to the arterial phase images. R-CTA images were then obtained by subtracting the warped images from the arterial phase images. The accuracies of using nonrigid registration and conventional spinal CTA and the time required for detecting arterial feeders in spinal arteriovenous fistulas were analyzed for each patient with DSA results as a standard reference. The difference between R-CTA and conventional spinal CTA was assessed by the Welch test and the McNemar χ(2) test. R-CTA had a higher accuracy compared with conventional spinal CTA (80% versus 47%, P = .025). The time for interpretation was reduced in R-CTA compared with conventional spinal CTA (45.1 versus 97.1 seconds, P = .002). Our subtracted CTA imaging by using nonrigid registration detects feeders of spinal arteriovenous fistulas more accurately and quickly than conventional CTA.

Timing-Invariant CT Angiography Derived from CT Perfusion Imaging in Acute Stroke: A Diagnostic Performance Study.

Timing-invariant (or delay-insensitive) CT angiography derived from CT perfusion data may obviate a separate cranial CTA in acute stroke, thus enhancing patient safety by reducing total examination time, radiation dose, and volume of contrast material. We assessed the diagnostic accuracy of timing-invariant CTA for detecting intracranial artery occlusion in acute ischemic stroke, to examine whether standard CTA can be omitted. Patients with suspected ischemic stroke were prospectively enrolled and underwent CTA and CTP imaging at admission. Timing-invariant CTA was derived from the CTP data. Five neuroradiologic observers assessed all images for the presence and location of intracranial artery occlusion in a blinded and randomized manner. Sensitivity and specificity of timing-invariant CTA and standard CTA were calculated by using an independent expert panel as the reference standard. Interrater agreement was determined by using κ statistics. We included 108 patients with 47 vessel occlusions. Overall, standard CTA and timing-invariant CTA provided similar high diagnostic accuracy for occlusion detection with a sensitivity of 96% (95% CI, 90%-100%) and a specificity of 100% (99%-100%) for standard CTA and a sensitivity of 98% (95% CI, 94%-100%) and a specificity of 100% (95% CI, 100%-100%) for timing-invariant CTA. For proximal large-vessel occlusions, defined as occlusions of the ICA, basilar artery, and M1, the sensitivity and specificity were 100% (95% CI, 100%-100%) for both techniques. Interrater agreement was good for both techniques (mean κ value, 0.75 and 0.76). Timing-invariant CTA derived from CTP data provides diagnostic accuracy similar to that of standard CTA for the detection of artery occlusions in acute stroke.

Quantitative evaluation of noise reduction and vesselness filters for liver vessel segmentation on abdominal CTA images

Liver vessel segmentation in CTA images is a challenging task, especially in the case of noisy images. This paper investigates whether pre-filtering improves liver vessel segmentation in 3D CTA images. We introduce a quantitative evaluation of several well-known filters based on a proposed liver vessel segmentation method on CTA images. We compare the effect of different diffusion techniques i.e. Regularized Perona–Malik, Hybrid Diffusion with Continuous Switch and Vessel Enhancing Diffusion as well as the vesselness approaches proposed by Sato, Frangi and Erdt. Liver vessel segmentation of the pre-processed images is performed using a histogram-based region grown with local maxima as seed points. Quantitative measurements (sensitivity, specificity and accuracy) are determined based on manual landmarks inside and outside the vessels, followed by T-tests for statistic comparisons on 51 clinical CTA images. The evaluation demonstrates that all the filters make liver vessel segmentation have a significantly higher accuracy than without using a filter (p < 0.05); Hybrid Diffusion with Continuous Switch achieves the best performance. Compared to the diffusion filters, vesselness filters have a greater sensitivity but less specificity. In addition, the proposed liver vessel segmentation method with pre-filtering is shown to perform robustly on a clinical dataset having a low contrast-to-noise of up to 3 (dB). The results indicate that the pre-filtering step significantly improves liver vessel segmentation on 3D CTA images.